Thermostat.



PATENTED AUG. 27, 1907.

F. W. ROBERTSHAW.

THERMOSTAT. APPLICATION FILED ooT. z5. moe.

`FREDERICK W. ROBERTSHAW, OF PITTSBUBG, PENNSYLVANIA. I

THERMOSTAT. I

r JJecication of Letters Patent.

Patented Aug. 27, v19,07.

Application filed October 25,1906. Serial No. 340.581.

To all whom it may concern:

Be it known that I, FREDERICK W. RoBuRTsHAw, a resident of Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Thermostats; and I do hereby declare the following to be a full, clear, and exact description thereof.

My invention relates to thermostats and gas valves -or controlling the ow of gas to the burners in water or like heaters, the varying temperature of the water acting indirectly to operate the valve to increase or' diminish the supply of gas as may be requiredto maintain the water at theproper temperature.

.The main objectief my invention is to provide a thermostat in which the coefficient of linear expansion oi one member which acts to operate the valve is so low that practically no account need be taken of it, whereby the exact movement of the valve may be calculated to a nicety.

A further object of my invention is to provide for the adjustment of the movement of the valve so that when once the desired temperature has been acquired, the valve may be adjusted so as to maintain the water at such temperature.

To these ends my invention comprises, generally stated, a thermostat comprising a valve casing having inlet and outlet ports, a valve and seat therefor, a section of -tubing connected to said casing, a rod ofcompressed carbonaceous material incased by said tube, the coeicient of linear expansion of the tubing b/eing greater than that of the rod, whereby the rod acts to operate the valve by the expansion of the tubing.

My invention further comprises certain other novel features, all of which will be fully set forth and claimed.

In the accompanying drawing Figure 1 is a side elevation of a water heater showing my improved thermostat applied thereto, the water reservoir being shown in sections; Fig. '2 is' an enlarged sectional view of my improved thermostat showing the connections leading thereto; and Fig. 3 is an enlarged plan view.

invention'may be applied to an ordinary hot water heater such as is employed in dwelling houses, or employed in connection with a hot water heating system or to a steam line. I have illustrated my invention as connected with a hot water heater, in which the numeral 2 vdesignates a suitable tank or receptacle having the inlet pipe 3 extending down into the tank. From the bottom of the tank 2 leads the pipe 4 which is connected up to the heater or coil 5` provided with the burner 7 connected up to pipe 8, a suitable, mixer 9 being employed. The pipe 10 leads from the upper end of the coil 5, and said pipe is connected .with the service pipe 11.

The main gas pipe 13 is provided with the valve 14 and is connected up to the val ve casing 15. The pipe 8 is connected up to the opposite side ofthe valve casing 15. Within the valve casing 15 is the valve seat 16, with which the valve 17 is adapted to engage to open and close the port 18. The valve 18 has the stud or projection 19 which is adapted to enter the recess 20 in the cap 21, which is secured to thecasing 15. A spring 22 encircles the stud 19 and bears ,at one end against the valve, and at the other end against its seat. The fiange 17 has the projection 23 which extends within the hub 24 of the casing. This hub 24 has the internal flange or shoulder 25, against which the Washer 26 rests. A threaded nut 27 engages the threaded seat in the hub 24 and is adapted to press the Washer 26 against the shoulder 25 to form a packing joint. A stem 28 passes through the nut 27, the said stem being threaded at its end as at 29 to engage with the threads formed within g the valve 17. This vstem 28 is provided with the head 30. The valve 17 is provided with the lugs or ears 17n and between said lugs the inner end of pin 17 b enters. This pin enters a threaded opening in the valve cap. The object of said pin' is to prevent the rotation of the valve by the turning of the adjustable stem 28, in case said stem should be diflicultto turn.

Bearing against the head 30 of the stem 28 is the short arm or lever 31, pivoted at 32 to the yoke 33 ofthe casing. l13 earing against the short lever 31 is the long lever 34, which brings the lug 35 in engagement with said lever adjacent to its pivotal point. The long lever 34 n is pivoted at 36 to the yoke 33.

The nut 37 is threaded into the yoke 33 and said nut has the threaded neck tapped into the tank 2, which is provided with the nipple 39 so as to connect said nut securely to the tank and provide a tight- -joint at this point to prevent leakage.

A tube 40 formed of copper or other suitable metal is threaded into the neck 38 of nut 37, said tubing projecting into the tank 2 for a suitable distance and being closed at its inner end by the plug 41. Contained within the tube 40 is the rod 42 formed of carbonaceous Inaterial, such as graphite, coke or lampblack. For this purpose I may vemploy the ordinary carbons used in electric are lighting. At the outer end of the rod 42 is secured the ferrule 43 which may be formed oibrass or other suitable metal. A like errule 44 is provided at the inner end of the rod 42 which bearsagainst the long lever 34. I prefer to have the axial line of the rod 42 in line with the axial line of the valve stem' 28, so that the pressure is on a direct line, while at the same time I provide a compound lever formed of the levers 3l and 34, whereby the movement of the rod 42 is compounded.-

When my improved thermostat is in use in connec" .tion with the form of apparatus described and illustrated, the gas is lighted at the burner 7 and the watery passing from the tank 2 up to the coil 5 is heated and passed from the pipe 10 back by the pipe 11 to the tank 2, creating' a circuit in this manner. The action of the spring 22 is to normally hold the valve 147 closed, However, when the water is below a certain temperature, the rod 442 is arranged to exert a pressure on the lever 34, which throughthe lever 31 acts to move the valve stem 28 sufficiently-to unseat the valve and gas passes through' the pipe 13 into the pipe 8 to the burner, When the water in the tank 2 becomes heated above a certain temperature the tubing 40 will be elongated, and as it elongates the pr'essure of the spring 22 Will act to close the valve and force the rod 42 to the outer end of the tube 40. IIn this manner the gas supply is shut off except what enters the valve casing by the by-pass 45, which is sufficient to keep the burner 7 lighted.

As the water is drawn from the tank 2 by the service pipe 11, the temperature is reduced by the incoming supply of cold water from pipe 3, and as the tempera; ture of the tube 40 is reduced said tubing contracts and by its contraction the rod 42 is forced against the level,`

v 34 and this movement is compounded by the lever 31,

so as to move the valve stem 28 suiiciently to open the valve to permit the gas to pass vfrom the pipe 13 into the pipe 8 and thence to the burner. This gives a greate supply of gas, and as a consequence the water in the coil 5 isl highly heated and the circuit is maintained in the manner before described. AAs the water continues to be dravvn through the service pipe ll'the valve -will remain open so as to supply the necessary hot Water, but after the service pipe is closed, the Water will then flow back into the tank 2 and when the temperatureof the vvater in the tank 2 has been raised to a ate very accurately to maintain the Water at the desired temperature. By compoundingthe levers in the manner illustrated, the movement of the rod -42 is compounded so vas to get a greatly increased movement on the valve stem 28.

By the employment of a rod composed of a material having a very low coefficient of linear expansion, the amount of the expansion and contraction of the rod 42 is so inappreciable that` it does not have to be taken into account, and as a consequence the expansion and contraction of the tubing when once determined is the only factor to be taken into consideration.

It is apparent that my improved device is also applicable to steam traps for the trapping and discharging of condensed steam Vfrom any steam line employing the variation of temperature to operate the thermostat.

What I claim is:

In a thermostat, the combination of a valve casing having inlet and outlet ports, a valve and seat, a section of tubing connected to said casing, a rod of compressed carbonaceous material incased by said tubing, and means for operating said valve by said rod.

In testimony whereof, I the said FREDERICK'W. Ronn'i SHAW have hereunto set my hand.

FREDERICK W. ROBERTSHAW.

Witnesses:

ROBERT C. To'r'rEN, Ron'r. D. TOTTEN.) 

